As a temperature-compensated crystal oscillator circuit using a crystal oscillator for obtaining a stable frequency, a Colpitts oscillator circuit 4 as shown in FIG. 8 is available. Since this circuit 4 oscillates when crystal oscillator X exhibits inductive impedance, a variable capacitance diode VD.sub.2 is connected in series with the oscillator X. A control voltage V.sub.D which is produced using thermistors TH.sub.3 and TH.sub.4 as temperature transducers is applied across the diode VD.sub.2 to produce a temperature-compensated oscillation frequency. Because the control voltage V.sub.D is applied across the diode VD.sub.2 over the whole temperature range in which compensation is made, the range depends upon the temperature characteristics of the thermistors TH.sub.3 and TH.sub.4. Therefore, as shown in FIG. 9 which is the same as FIG. 10 of Japanese Patent Publication No. 34091/1972, the temperature characteristic of the thermistor TH.sub.3 differs widely from that of the thermistor TH.sub.4 at low temperatures. In FIG. 9, the curves indicated by the circled dots and the broken line are obtained under the conditions of designed values m=0.85 and m=1, respectively. This gives rise to error in the control voltage which is generated for temperature compensation. Hence, it is difficult to provide temperature compensation over a broad temperature range, as for example, from -30.degree. C. to +70.degree. C. More specifically, if such an error should be minimized, each different resistance value is selected for each individual oscillator circuit in a quite cumbersome manner. Also, if the crystal oscillator is kept at a constant temperature, a large amount of electric power is consumed, making low consumption of electric power unfeasible.